1. Field of the Invention
The present invention relates to an apparatus for generating ICP (inductively coupled plasma), and more particularly, to an apparatus for generating ICP, enabling to reduce occurrence of undesirable particles.
2. Description of the Related Art
Semiconductor processing equipments using plasma are generally classified into etching equipment and depositing equipment. When a semiconductor process is performed in the semiconductor processing equipment, by-products are inevitably adhered to elements and inner wall of a chamber. The adhered by-product acts as a source that generates undesirable particles during the semiconductor process, thereby degenerating the productivity.
In order to restrain the generation of the particles, the adhesion of the by-product has to be restrained. Further, in order to restrain the adhesion of the by-product, there is used a method of heating the elements or the inner wall of the chamber. As examples of such the heating method, there are a radiant heating method using a halogen lamp, a heat conduction method using a heater, and a heat convection method using hot air. These methods are selectively used depending on kinds or situations of process.
FIG. 1 is a schematic view of a conventional apparatus for generating ICP. Referring to FIG. 1, a chamber 10 provides a hermetical space for performing a plasma process. The hermetical space is divided into three spaces horizontally by an antenna plate 20 and a gas distribution plate 30. The gas distribution plate 30 is placed below the antenna plate 20.
A plurality of injecting holes are formed in the gas distribution plate 30. Between the antenna plate 20 and the gas distribution plate 30, there is disposed a reaction gas supplying port (not shown). A reaction gas introduced through the reaction gas supplying port to a space between the antenna plate 20 and the gas distribution plate 30 is injected through the injecting holes of the gas distribution plate 30 to a space below the gas distribution plate 30. At the lower space of the gas distribution plate 30, there is formed a reaction gas discharging port (not shown). The reaction gas injected to the lower space of the gas distribution plate 30 is converted into a plasma state by an electromagnetic field formed by an RF antenna 25 mounted on the antenna plate 20. Reflectance of RF power applied to the RF antenna 25 is minimized through a matching box 50.
Since the gas distribution plate 30, the inner wall of the chamber 10 and the antenna plate 20 are exposed to the plasma and the by-product such as polymer is deposited to surfaces of the inner wall and the antenna plate 20 during the process. The deposited by-product is served as a source that generates undesirable particles during the process. Therefore, in order to reduce the deposition of the by-product, a plurality of halogen lamps 45 for heating the elements of the chamber 10, such as the gas distribution plate 30, and the inner wall of the chamber 10 are disposed over the antenna plate 20. The halogen lamp 45 is fixed by a lamp supporting plate 40.
If the halogen lamp 45 is excessively apart from the antenna plate 20, an intensity of the light arrived at the antenna plate 20 is rapidly reduced. Therefore, there occurs a problem in that the gas distribution plate 30 is not sufficiently heated. This is because the intensity of light arrived at the antenna plate 20 is inversely proportional to a square of a distance between the antenna plate 20 and the halogen lamp 45. If the halogen lamp 45 is disposed to be adjacent to the antenna plate 20 in order to prevent the foregoing problem, an RF noise phenomenon occurs due to a high frequency generated from the RF antenna 25. Further, there is a problem that a distribution of heat arrived at the antenna plate 20 and the gas distribution plate 30 is not uniform.
Therefore, in order to equally heat the gas distribution plate 30 while the halogen lamp 45 is not influenced by the RF noise, the halogen lamp 45 has to be apart from the antenna plate 20 at a proper distance. However, in this case, the gas distribution plate 30 is heated only at a temperature of 70xcx9c80xc2x0 C. Therefore, there is a problem that the gas distribution plate 30 is not sufficiently heated.
According to the conventional apparatus for generating ICP, in order to sufficiently heat the elements within the chamber 10, such as the gas distribution plate 30, and the inner wall of the chamber 10 without the generation of the RF noise phenomenon, the halogen lamp 45 has to be apart from the antenna plate 20 at a long distance and the number of halogen lamps 45 also has to be increased. However, in this case, there are some problems that an operation and an installation of the halogen lamp 45 are complicated and fabrication and operation costs are increased.
Therefore, it is an object of the present invention to provide an apparatus for generating ICP, which is capable of heating the elements in the chamber and inner wall of the chamber without generation of the RF noise.
To achieve an aforementioned object of the present invention, there is provided an apparatus for generating ICP, the apparatus comprising a chamber providing a hermetical space; an antenna plate disposed to horizontally divide the hermetical space; a gas distribution plate disposed to horizontally divide a space below the antenna plate and having a plurality of injecting holes; a reaction gas supplying port disposed at a space between the antenna plate and the gas distribution plate so as to inject a reaction gas through the injecting holes of the gas distribution plate to a space below the gas distribution plate; a reaction gas discharging port disposed to discharge the reaction gas injected to the lower space of the gas distribution plate; an RF antenna for forming plasma at the lower space of the gas distribution plate, which is mounted on the antenna plate; a heating plate for heating the chamber, which is disposed to horizontally divide a space above the antenna plate and which has a plurality of air holes; a heat transferring gas supplying port disposed at a space above the heating plate so as to inject a heat transferring gas through the air holes of the heating plate to a space between the heating plate and the antenna plate; and a heat transferring gas discharging port disposed to discharge the heat transferring gas injected to the space between the heating plate and the antenna plate.
Preferably, the heating plate is comprised of a two-layered aluminum plate having a recessed groove at a junction portion therebetween, a hot wire disposed in the recessed groove along the recessed groove, and an insulating member enclosing the hot wire. Alternatively, the heating plate is comprised of a two-layered aluminum plate, a plate type hot wire interposed between the two layers of the aluminum plate, and an insulating member enclosing the hot wire.
Meanwhile, it is preferable that the gas distribution plate is disposed according to an equation as follows;             10      xc3x97              (                              ϵ            air                                ϵ            ⁢                          xe2x80x83                        ⁢            p                          )            xc3x97      D        ≺    d    ≺          100      xc3x97              (                              ϵ            air                                ϵ            p                          )            xc3x97      D        ,
where d is a distance between the heating plate and the antenna plate, xcex5p is an entire dielectric of the antenna plate and the gas distribution plate, xcex5air is a dielectric of air between the heating plate and the antenna plate, and D is an entire thickness of the antenna plate and the gas distribution plate.
Further, it is preferable that the air holes of the heating plate are disposed in two concentric circles respectively having radiuses ra and rb from a center of the heating plate, and a difference between the number of air holes disposed in the radius ra and the number of air holes disposed between the radiuses rbxe2x88x92ra is in an extent of 20%.
Preferably, the air holes of the heating plate is disposed according to an equation as follows:             [                                    (                                          r                b                                            r                a                                      )                    2                -        1            ]        xc3x97    0.8    ≤            N              b        -        a                    N      a        ≤            [                                    (                                          r                b                                            r                a                                      )                    2                -        1            ]        xc3x97    1.2  
where Na is the number of the air holes disposed in the radius ra, and Nbxe2x88x92a is the number of the air holes disposed in the radius rbxe2x88x92ra.
Further, it is preferable that the apparatus further comprises flow-meters disposed at each of the heat transferring gas supplying and discharging ports to be capable of controlling a flow rate of the transferring gas, and a feedback device comparing a temperature of the antenna plate with a desired reference temperature and outputting a controlling signal to the flow-meters so as to maintain the temperature of the antenna plate at the desired reference temperature.
Preferably, the apparatus further comprises a heat insulating plate and a water cooling line disposed at the inner wall of the chamber located at an upper portion of the antenna plate.